The ability of certain factors produced in very low concentration in a variety of tissues to stimulate the growth and development of bone marrow progenitor cells into granulocytes and/or macrophages has been known for nearly 15 years. The presence of such factors in sera, urine samples, and tissue extracts from a number of species is demonstrable using an in vitro assay which measures the stimulation of colony formation by bone marrow cells plated in semi-solid culture medium. There is no known in vivo assay. Because these factors induce the formation of such colonies, the factors collectively have been called Colony Stimulating Factors (CSF).
More recently, it has been shown that there are at least four subclasses of human CSF proteins which can be defined according to the types of cells found in the resultant colonies. One subclass, CSF-1 results in colonies containing macrophages predominantly. Other subclasses produce colonies which contain both neutrophilic granulocytes and macrophages; which contain exclusively neutrophilic granulocytes; and which contain neutrophilic and eosinophilic granulocytes and macrophages.
There are murine factors analogous to the first three of the above human CSFs. In addition, a murine factor called IL-3 induces colonies from murine bone marrow cells which contain all these cell types plus megakaryocytes, erythrocytes, and mast cells, in various combinations. These CSFs have been reviewed by Dexter, T. M., Nature (1984) 309:746, and Vadas, M. A., et al, J Immunol (1983) 130:793.
The invention herein is concerned with the recombinant production of proteins which are members of the first of these subclasses, CSF-1. This subclass has been further characterized and delineated by specific radioimmunoassays and radioreceptor assays--e.g., antibodies raised against purified CSF-1 are able to suppress specifically CSF-1 activity, without affecting the biological activities of the other subclasses, and macrophage cell line J774 contains receptors which bind CSF-1 specifically. A description of these assays was published by Das, S. K., et al, Blood (1981) 58:630.
A significant difficulty in putting CSF proteins in general, and CSF-1 in particular, to any useful function has been their unavailability in distinct and characterizable form in sufficient amounts to make their employment in therapeutic use practical or even possible. The present invention remedies these deficiencies by providing purified human and murine CSF-1 in useful amounts through recombinant techniques.
(A CSF protein of a different subclass, murine and human GM-CSF, has been purified and the cDNAs have been cloned. This protein was shown to be distinct from other CSFs, e.g., CSF-1, by Gough, et al, Nature (1984) 309:763-767. This GM-CSF protein is further described in W087/02060, published Apr. 9, 1987 as being useful to treat cancer patients to regenerate leukocytes after traditional cancer treatment, and to reduce the likelihood of viral, bacterial, fungal and parasitic infection, such as acquired immune deficiency syndrome (AIDS). Murine IL-3 has been cloned by Fung, M. C., et al, Nature (1984) 307:233. See also Yokota, T., et al, Proc Natl Acad Sci (U.S.A.) (1984) 81:1070-1074; Wong, G. G., et al, Science (1985) 228:810-815; Lee, F., et al, Proc Natl Acad Sci (U.S.A.) (1985) 82:4360-4364; and Cantrell, M. A., et al, Proc Natl Acad Sci (U.S.A.) (1985) 82:6250-6254.)
Treatment of patients suffering from AIDS with CSF-1, alone or together with erythropoietin and/or an antiviral agent and/or IL-2 is reported in W087/03204, published June 4, 1987. U.S. Pat. No. 4,482,485, issued Nov. 13, 1984 states that CSF can be used for a supporting role in the treatment of cancer. In addition, EP 118,915, published Sept. 19, 1984 reports production of CSF for preventing and treating granulocytopenia and macrophagocytopenia in patients receiving cancer therapy, for preventing infections, and for treating patients with implanted bone marrow. In addition, CSF-1 is reported to stimulate nonspecific tumoricidal activity (Ralph et al, Immunobiol (1986) 172:194-204). Ralph et al, Cell Immunol (1983) 76:10-21 reported that CSF has no immediate direct role in activation of macrophages for tumoricidal and microbiocidal activities against fibrosarcoma 1023, lymphoma 18-8, and L. tropica amastigotes. Ralph et al, Cell Immunol (1987) 105:270-279 reports the added tumoricidal effect of a combination of CSF-1 and lymphokine on murine sarcoma TU5 targets. Copending U.S. application Ser. No. 948,159, filed Dec. 31, 1986, now abandoned discloses use of CSF-1 and G-CSF.
In addition, Warren et al, J Immunol (1986) 137:2281-2285 discloses that CSF-1 stimulates monocyte production of interferon, TNF and colony stimulating activity. Lee et al, J Immunol (1987) 138:3019-3022 discloses CSF-1-induced resistance to viral infection in murine macrophages.